1. Field of the Invention
The present invention relates to a manufacturing apparatus for slide fastener (e.g., zipper) continuous element row and more particularly to an improved apparatus for manufacturing slide fastener spiral continuous element row.
2. Description of Related Art
A coupling head forming portion of a conventional apparatus for manufacturing slide fastener continuous element row is disclosed in U.S. Pat. No. 6,302,676, as shown in FIG. 8. The apparatus comprises a pair of screws 1, a die 2, a coupling head forming disc 3, a mandrel 4 between the die 2 and the forming disc 3, a core thread 5 received in a longitudinal recess of the mandrel 4, and an element 6 received in a space defined by the die 2 and the coupling head forming disc 3, the element 6 having a joint portion 6a and an coupling head 6b formed by the coupling head forming disc 3.
Typically, a diameter of the screw 1 is limited to a predetermined maximum value. This is because as the diameter of the screw 1 increases an insertion space of the die 2 decreases due to a change of curvature. That is, two necks 2a of the die 2 are required to conform with diameters of the screws 1. Otherwise, there is a possibility of interference between the neck 2a and the screw 1 at either side of the coupling head forming disc 3. Typically, the diameter of the screw 1 is at a range between 5 mm and 8 mm such as in the case of zipper numbered 3 to numbered 7. In a special case, the diameter of the screw 1 has a maximum value of 10 mm such as in the case of zipper numbered 9 and numbered 10.
However, the prior art suffered from several disadvantages. For example, the diameter of the screw 1 cannot exceed the maximum value. As such, a diameter of a shaft 3a of the coupling head forming disc 3 also cannot exceed a predetermined maximum value. As shown, the diameter of the shaft 3a is about one fifth of that of the screw 1. Otherwise, there is a possibility of interference between the shaft 3a and the screw 1 at either side of the coupling head forming disc 3. Typically, the diameter of the shaft 3a is about 2 mm. Hence, the coupling head forming disc 3 may vibrate strongly due to a high forming pressure and rotation of the coupling head forming disc 3 in the manufacturing process of the element 6. In brief, a strength of the shaft 3a is not sufficient. Further, a size of the die 2 is limited because the screw 1 is received in the die 2. As such, the screw 1, the die 2, and the coupling head forming disc 3 are also limited in size. In other words, allowable increases of the coupling head forming disc 3 and the shaft 3a are also limited. As a result, it is difficult to totally eliminate the vibration. Furthermore, a space available to the necks 2a as provided by the screws 1 is relatively small even if all of the screw 1, the die 2, and coupling head forming disc 3 increase in size. In such case, the necks 2a may become sharp (i.e., smaller cross-sections) for conforming with the diameters of the screws 1. This can reduce a contact area in the manufacturing process of the element 6. In response, the joint portion 6a of the element 6 may recess (i.e., deformed). As a result, it is difficult to totally eliminate the vibration since the strength of the shaft 3a is not sufficient and the limitation of sizes of the screw 1, the die 2, and the coupling head forming disc 3. Moreover, a precision of the element 6 may be adversely affected because a size of the mandrel 4 is small and the mandrel 4 tends to wear (i.e., size changed) or the size of the mandrel 4 exceeds an allowance due to machining error. At this time, an appropriate adjustment of locations of the necks 2a, the mandrel 4, and the coupling head forming disc 3 is required. However, such adjustment is very difficult because the necks 22 are integral part of the die 2 and the coupling head forming disc 3 rotates about the shaft 3a. 
Thus, it is desirable to provide an apparatus for manufacturing slide fastener spiral continuous element row in order to overcome the above drawbacks of the prior art.
It is an object of the present invention to provide an apparatus for manufacturing slide fastener spiral continuous element row wherein a rear forming assembly is secured to a rear abutment plate and a forming screw assembly can effect a stable, very little vibration operation with the cooperation of a main spring, a shaft mechanism and a rear adjustment screw. Thus, high quality products are manufactured.
In one aspect of the present invention, a fine adjustment is made in rear of an abutment assembly so that the adjustment is made easy and simple.
In another aspect of the present invention, a fine adjustment of the forming screw assembly may be done in any time so as to provide an optimal zipper forming space. Also, a mandrel can be corrected if a precision thereof is adversely affected due to wear.
In still another aspect of the present invention, once a size of the mandrel exceeds an allowance due to machining error it is still possible of being corrected by a fine adjustment of the forming screw assembly. Thus, the optimal zipper forming space still can be obtained and a desired precision of the element still can be maintained.
In still another aspect of the present invention, a lateral fine adjustment of the forming screw assembly can be made in any time so as to obtain a more precise positioning of the forming screw assembly for increasing the precision of the element.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.